Medical devices should be here understood under their broadest meaning, i.e. devices useful for the prevention, cure, alleviation, or correction of diseases, injuries, irregularities, disorders and deformities of any part of a human or animal body. They include not only devices useful for the prevention, cure or alleviation of diseases by non operative procedures, but also surgical devices (i.e. devices which treat diseases or injury by operative procedures), dental devices (i.e. devices useful for the prevention, cure or alleviation of diseases of the teeth, orthodontic devices (i.e. devices useful for the prevention or correction of irregularities of the teeth) and orthopedic devices (i.e. devices useful for disorders or deformities of the spine and joints) and the like.
Medical devices are made from a variety of materials, such as metal and polymers. They are generally sterilized. Because of their functionality, they need generally to have a complex design.
Parts of medical devices having very complex shapes are often needed notably for orthodontic and orthopedic devices. As an illustration of parts of orthodontic devices having a complex shape, orthodontic brackets, can be cited. As an illustration of parts of orthopedic devices having a complex shapes, hip rasps can be cited.
Parts of medical devices having a very low thickness are also often needed, notably for medical tubings, orthodontic devices, medical films and coatings.
Medical tubings, useful notably for catheters and guidewires, feature typically diameters that measure thousandths of an inch, with walls thinner than a human hair; to produce medical tubings with extremely thin walls, manufacturers force material to flow through the small orifices of processing equipment. As an illustration of parts of orthodontic devices having a very low thickness, orthodontic wires can be cited. As an illustration of medical coatings, biocidal coatings coated on the inner and/or outer walls of catheters can be cited.
Material selection is often crucial for medical devices. Engineering polymers, such as polyetheretherketones, polysulfones, polycarbonates, polyurethanes and polyamides, are generally preferred over metal because of their light weight and ability to be shaped into complex shapes and articles having a very low thickness, while exhibiting a reasonably good balance of properties.
An important problem when using the above engineered polymers for medical applications is that they do not generally achieve the desirable level of stiffness. It has already been attempted to solve this problem by providing medical devices, such as catheters, guidewires, orthodontic wires made of certain polyarylenes of the “first two generations”.
WO 2005/102406 (to Boston Scientific Scimed) and WO 2006/037078 (to Cordis Corp.), the whole content of which is herein incorporated by reference, describe medical devices, such as catheters, made from certain rigid-rod polyparaphenylenes. Parmax® 1000, a rigid-rod poly-1,4-(benzoylphenylene) homopolymer of the first generation, was anciently developed and commercialized by Mississippi Polymer Technologies under the trademark Parmax® SRP (SRP for “Self-Reinforcing Polymers”).
WO 2006/008739 (to the University of Connecticut) describes an orthodontic appliance including an orthodontic component, such as an orthodontic bracket or wire, comprising either Parmax® 1000 (namely, a rigid-rod polyparaphenylene), or Parmax® 1200, a random copolymer of benzoyl appended 4,4-phenylene (15 mol. % of the repeat units) and 1,3-phenylene (85 mol. % of the repeat units, now commercialized by Solvay Advanced Polymers as Primospire™ PR-120. This polyphenylene of the second generation, commonly referred to as kinked rigid-rod polyphenylene (because it comprises p-phenylene and m-phenylene repeat units), can be further characterized by the presence of a high amount of p-phenylene, rigid-rod forming units and a low amount of m-phenylene, kink-forming units.
Unfortunately, because of the intrinsic rigid nature of the so-proposed polyarylenes of the 1st two generations, shaping them into articles having complex shapes or with a very low thickness by melt processing techniques such as injection molding or extrusion, was very difficult. For example, extruding them into medical tubings (with extremely thin walls) or orthodontic wires (with small diameters), is extremely difficult. In practice, such rigid-rod polyphenylene need to be solvent-casted into thin films from various solvent mixtures, such as NMP, with all the economic and environmental drawbacks linked to the use of solvents.
WO 02/072007 (to the University of Pennsylvania) describes various facially amphiphilic rigid-rod polyarylenes, which are generally reported to be suitable notably for being incorporated in, or attached to a catheter. In particular, WO 02/072007 describes polyparaphenylenes homopolymers substituted with polar groups (—P) and non polar groups (—NP), such as polymers having the general formula
it describes also facially amphiphilic kinked polymetaphenylenes homopolymers substituted with polar groups (—P) and non polar groups (—NP), such as:

On the other hand, WO 02/072007 keeps totally silent on the mechanical properties, such as the stiffness, and melt-processability of the so-disclosed amphiphilic rigid-rod polyparaphenylenes and amphiphilic kink rigid-rod polymetaphenylenes. The Applicant, which has developed a big experience on polyphenylenes and their processing, is of the opinion that the amphiphilic rigid-rod polyparaphenylenes of WO'007 suffer from a poor processability, especially a poor injection-moldability and a poor extrudability, while the amphiphilic rigid-rod polyparaphenylenes of WO'007 exhibit a low stiffness, and, probably too, they further exhibit a poor processability, especially a poor injection-moldability and a poor extrudability.
Another important problem when using the above mentioned polymers for medical applications is that they do not generally achieve the desirable level of impact resistance (as typically characterized by standard notched and unnotched Izod tests).
In general some of, the above mentioned polyphenylenes, while offering an exceptionally high level of strength and stiffness (which often even exceeds the needs of the applications wherein they are used) suffer irremediably from a limited impact resistance. This property may be useful in certain demanding applications, such as articles used as medical devices.
There is thus an important need for medical devices including parts exhibiting a confluence of characteristics including high stiffness, high torqueability, high pushability, high flexibility and a very good impact resistance, and which can be easily formed by melt-processing techniques, such as extrusion or injection-molding, including when the parts of concern have a complex shape and/or a very low thickness (e.g. by using an extruder with extremely small orifices).